Trends of radiotherapy for hepatocellular carcinoma in the Republic of Korea: a national cohort, 2013–2021

Purpose: This study aimed to investigate national trends of radiotherapy (RT) in the initial treatment course of hepatocellular carcinoma (HCC) using the National Health Information Database (NHID) in the Republic of Korea, 2013-2021. Materials and Methods: Patients newly diagnosed with HCC (2013-2021) were identified from the NHID, excluding those with another malignancy within 5 years, without active treatment, or without health insurance. The initial treatment course was defined as any modality administered within 6 months of registration. Annual and regional trends in RT utilization, techniques, and co-administration of multiple modalities were evaluated, including a temporal sensitivity analysis comparing early (2013-2016) and late (2017-2021) periods. Results: Among 64,808 eligible patients, 72.4% received a single modality and 27.6% multiple modalities. RT was administered as single- or dual-modality treatment to 5,622 patients (8.7%). It was more often combined with another modality than alone, most frequently with transarterial chemoembolization (TACE; n = 3,329). Single-modality RT increased from 1.6% (2013) to 2.9% (2019-2020). The RT landscape shifted markedly: three-dimensional conformal RT fell from 84.6% to 19.7%, intensity-modulated RT rose from 2.4% to 47.4%, and proton beam therapy (PBT) emerged (15.8% by 2021). These shifts were concentrated in the late period, when PBT (1.6% to 10.8%) and TACE + RT both increased significantly (p < 0.001). The capital region (Seoul and Gyeonggi-do) managed 67.4% of the cohort, where PBT was performed exclusively. Conclusion: The role of RT in HCC management has expanded substantially, becoming a core multidisciplinary component. However, overall RT utilization remains concentrated in the capital region, reflecting the structural centralization of RT infrastructure.